参考答案

正确答案：international airfreight。
international airfreight。 解析：由题眼定位到小标题Overseas Expansion下第二段末段：Included in the acquisition were routes to 21 countries，a fleet of Boeing 747 and 727 aircraft，facilities throughout the world and Tigers' expertise in international airfreight(公司还同时获得了在亚洲21个国家的航线权，一支Boeing 747 and 727飞机舰队，飞虎公司在全世界的设备以及飞虎公司在国际航空货运方面的专业知识)。题干中的special knowledge是对文章中expertise的解释，答案不难得出。